From the prior art, various methods are known for connecting metallic components using inductive HF pressure welding. Thus, for example DE 198 58 702 A1 describes a method for connecting blade parts of a gas turbine, a blade vane segment and at least one additional blade part being provided. Here, corresponding connecting surfaces of these elements are positioned at a distance from one another so as to be essentially in alignment, and are subsequently welded to one another through the excitation of an inductor with a high-frequency current, and through being brought together so that their connecting surfaces contact one another. Here, the inductor is excited with a constant frequency, generally greater than 0.75 MHz. The frequency is also selected as a function of the geometry of the connecting surfaces. In inductive HF pressure welding, the simultaneous and homogenous heating of the two parts being welded is of decisive importance for the quality of the join point. Up to now, the joining process was carried out in a manner controlled by force. However, a disadvantage of this is that the resulting parts may have different lengths or dimensions, with the use of identical components.
The object of the present invention is therefore to provide a method of the type indicated above for connecting metallic components, in which on the one hand a reliable and long-lasting connection of components is ensured, while on the other hand identical lengths or dimensions of the resulting parts are ensured with the use of identical components.
In addition, the object of the present invention is to provide a device of the type indicated above that ensures on the one hand a reliable and long-lasting connection of components and on the other hand ensures identical lengths or dimensions of the resulting parts with the use of identical components.
For the sake of clarity, it is here expressly noted that the designation “inductive HF pressure welding” does not limit the method or the device in the present case to a particular frequency range. Rather, frequencies are used ranging from the low kHz range up to the high MHz range, so that the new designation “inductive pressure welding” (IPS) could be introduced.
Advantageous constructions of the present invention are described in the respective subclaims.
A method according to the present invention for connecting metallic components, in particular components of a gas turbine, uses inductive HF pressure welding in order to connect corresponding connecting surfaces of the components. Here, advantageously during or after a sufficiently great heating of the connecting surfaces the first component is moved toward the second component by a defined path or distance W and is pressed against it and held there. In addition to a reliable and long-lasting connection of the components, this also ensures that the resulting parts will have identical lengths or dimensions given the use of identical components. In addition, this ensures a correct geometrical transition in the join zone of the two connecting surfaces. The correct geometrical transition also limits post-processing that may be required to this join area only. The method according to the present invention makes it possible for the first component to be capable of being moved in the direction of the second component, which itself is not capable of being moved in the direction of the first component. However, it is also possible for the first and the second component to be capable of being moved toward one another. The path W is standardly 0.5 mm to 10 mm.
In another advantageous realization of the method according to the present invention, in order to determine the quality of the resulting connection a measurement is carried out of the forces that occur during the pressing and holding process. This measurement is standardly carried out using at least one force sensor. In some exemplary embodiments, it has turned out that a force in the range of 200 N represents a reference value for an ideal Joining or connection of the components. If it is necessary to apply forces greater than 200 N, the join zone has not been sufficiently melted, or is not sufficiently “doughy.” Forces smaller than 200 N indicate that the join zone is too “doughy,” or has melted too much.
In another advantageous realization of the method according to the present invention, before and during the movement of the first component toward the second component a monitoring is carried out of the position and orientation of the components. The monitoring of the position and orientation is standardly carried out using an optical measurement device. The monitoring of the position and orientation ensures an optimal movement and pressing together of the components that are to be connected. In addition, if necessary, changes of position and orientation can be carried out during the movement of the components.
In another advantageous realization of the method according to the present invention, the first component is a blade or a part of a blade of a rotor in a gas turbine, and the second component is a ring or a disk of the rotor or is a blade root situated on the periphery of the ring or of the disk. These parts, assembled from the named components and manufactured according to the method of the present invention, are what are known as BLINGs (“bladed rings”) or BLISKs (“bladed disks”) of gas turbine engines. In these parts, it is of significant importance that the ends of the blades always have the same distance relative to the disks or rings, or that the blades have a uniform length.
A device according to the present invention for connecting metallic components, in particular components of a gas turbine, uses an inductive HF pressure welding process in order to connect corresponding connecting surfaces of the components. Here, the device has at least one transport device for moving the first component toward the second component by a defined path W, or for moving the first and second component toward one another by the defined path W, as well as for pressing and holding the components. The path-controlled guidance of the components ensures on the one hand a reliable and long-lasting connection of the components. On the other hand, it is ensured that the resulting parts will have identical lengths or dimensions, given the use of identical components. In addition, the path-controlled guidance ensures a correct geometrical transition in the join zone. Through the at least one transport device, the first component, for example a blade of a turbine engine, is moved toward the second component, for example what is known as a BLISK rotor, by the defined path W, and is pressed against it and held there until the connection zone or join zone has cooled. Here, the transport device can be a component mount. The path W is standardly 0.5 mm to 10 mm.
In another advantageous construction of the device according to the present invention, this device has at least one force sensor for measuring the forces that occur during the pressing and holding process. In some exemplary embodiments, it has turned out that a force in the range of 200 N represents a control quantity for an ideal joining or connecting of the components. If forces greater than 200 N have to be applied, the join zone has not melted enough, or is not “doughy,” or not doughy enough. In contrast, forces smaller than 200 N indicate that the join zone is too doughy or has melted too much.
In another advantageous construction of the device according to the present invention, the device has at least one position and orientation measurement device for monitoring the position and orientation of the components before and during the movement of the first component toward the second component. The monitoring of the position and orientation ensure an optimal movement and pressing against one another of the components that are to be connected. In addition, if necessary, changes in the position and orientation can be made during the movement of the components. The position and orientation measurement device is standardly an optical measurement device.
In another advantageous construction of the device according to the present invention, the first component is a blade of a rotor used in a gas turbine, or is a part thereof, and the second component is a ring or a disk of the rotor, or is a blade root situated on the periphery of the ring or of the disk. These parts, assembled from the named components, are what are known as BLINGs (“bladed rings”) or BLISKs (“bladed disks”) of gas turbine engines.
Additional advantages, features, and details of the present invention result from the following description of a graphically depicted exemplary embodiment.